Piston and head damaged with small holes,what to do?

hello guys.
I bought a 1996 200sx s14 sr20det project for a good price..And the previous owner said the pistons needed a change. but it looks like the valves have been changed after the the damage to the head and piston since it does not have the same little holes as the rest of the head.In other words some previous owner have just ignored the damage,so i wonder is it not that serious and the engine would run fine?
Do i need a new head or can it be saved by me(what can i do?) or a machinist? any suggestions what could have happen to make the damage?
All the other pistons are fine,only the number two piston and head is damaged..
PS:the holes does not go through the piston
Here is some pictures..
https://u.cubeupload.com/mikkime/t/IMG0200.jpg
https://u.cubeupload.com/mikkime/t/IMG0203.jpg

That's had something drop into there, maybe a plug end? The holes look too 'crisp' and big to be detonation, and that normally occurs on the squish pads first with sr20's, and they're fine. In my (non-expert) opinion, you need a new head. The Valves are a lot harder than the alloy head, so it's possible they've not got damaged, but it depends what foreign object ended up clattering about in the cylinder, and the intake valves look like they may have taken some hits?

strange that it hasn't knackered the squish pads.

thanks guys,i am gonna buy a new head,since it is cheap anyway:-)

What ever that was that was rattling around was significantly heavy to make those holes! have you checked the turbine wheel on the turbo?
In all honesty, if you were leaving the engine completely stock on standard boost you would probably never notice any adverse from that damage! (as long as the valves seats are undamaged).
But if you're planning on any boost upgrades then the holes/pitting will be an attraction for hot spots and detonation.